1. Field of the Invention
This invention relates to an actuating mechanism for use in a printing head of a printing machine, and more particular for use in a printing machine of the type in which a platen roller and a printing head are pressed against each other and in which either the platen roller or the printing head is swingably moved while the other one is fixed. The actuating mechanism of the present invention is especially suitable for a thermal transfer printer which prints labels or tags on a tape-like web using a carbon ribbon.
2. Description of the Prior Art
In conventional printing machines, the printing mode is set by moving or turning either a printing head or a platen roller. In a printing machine of the type in which the printing head is turned in order to press the printing head to the platen roller, a set spring is stretched betwen the printing head and an actuating means that comprises an actuating lever and engaging members. The tension of the set spring is exerted on the platen roller by means of the actuating device. An information recording medium, which is disposed under pressure between the platen roller and the printing head, is printed. The printing head that is released from the engaging means in the actuating device is caused to bump abrubtly against the platen roller by the tension of the spring. In this action, the printing head is liable to be damaged.